Patent GB-391864-A (GB)
Title: Improvements in or relating to metal-clad electric switchgear
IPC: H01H33/52
Filed: 1931-11-07
Abstract: 391,864. Switchgear structures ; oil-break switches. REYROLLE & CO., Ltd., A., Hebburn-on-Tyne, CHRISTIE, J., 4, Sidecliff Road, and DONKIN, A., 2, Montpelier- Terrace, both in Sunderland. Nov. 7, 1931, No. 30912. [Class 38 (v).] Switches, latching and unlatching; electricmotor actuation.-An interlocking mechanism for preventing incorrect operation of the individual switches of a system comprises a bar having slots or projections which co-operate with slots or projections on the actuating levers which are associated with the switches, the bar being movable longitudinally by means independent of the levers in such a manner as to prevent operation of any of the levers unless the bar has previously been moved into a position appropriate to such operation and to prevent movement of the bar into any operative position unless the levers are in appropriate positions. In the form shown, it is assumed that the levers 50-90, 120 actuate a cable earthing switch, transformer, cable, reserve and main bus-bar isolators, and a main circuit breaker respectively and the bar 100 which may be moved by handle 101 has five positions to permit various circuit changing and other operations. The lever 50, Fig. 11, has a slot which permits bar 100 to be moved except in the first position when closure of the lever 50 locks the bar by engaging a slot in it. Lever 120 is similar but the corresponding part of bar 100 has two slots, positions 1 and 4, whilst lever 60, which also has one slot, may be operated in any of positions 2 .. 5 since bar 100 has a slot extending over a length corresponding to these four positions. Lever 70 has slots 75, 76, Fig. 5, and the corresponding part of the bar has a slot so that it may be operated in the second position and has ribs 108, 109 so that the lever is locked off in the first but locked on (thrown forward) in the third, fourth, and fifth. Lever 80 has slots 83, 84 and the bar has ribs 108, 110 so that lever is locked off in positions 1, 2, 5, closable in 3, may be locked off in 4 or locked on if lever 90 is off. Lever 90 is similar to 80 but the bar has a rib for locking off in positions 1, 2, 3, the operating slot is at 5, and the lever is locked off at 4 or locked on if 80 is off. As an alternative to manual operation by handle 101, a. reversible motor driving through a slipping clutch 252 may be provided to move bar 100 which has contact plates 276, 277 co-operating with brushes 271 .. 275 connected to a selector switch for energizing the motor to move the bar to any one position according to the position of switch arm 260. Motor 280 mounted with the lever driving arrangements on bar 100 rotates shafts 287 or 288 through a right-angle according to whether clutch 282 or 283 is engaged, and these shafts carry pin bearing arms 290, Fig. 11, which engage, in the appropriate positions, levers 293 linked to the switch levers ; levers 50, 70, 80, 90 being actuated by shaft 287, 60 by 288, and 120 by 287 in the fourth bar position and 288 in the first. Pushbuttons 310, 315 respectively control the closing and opening of the lever 60 (and also in first bar position of 120), whilst buttons 320, 325 control the remaining auxiliary switches, and lever 120 in the fourth position. In an alternative form, the bar may have two positions for cable earthing, one phase being earthed first and the other two in the other position. An alternative arrangement for controlling the operation of the main circuit breaker is described. The selector bar may also be arranged to prevent energization of the device for lowering the circuitbreaker tanks unless the switches are in the isolating positions. An indicator is provided to show the position of the bar, and indicating lamps are provided to show the conditions of the controlled switches.